Process of making pigments.



UNITED STATES .lPatented September 29, 1903;

PATENT OFF E;

W LTJAM J. AR BRUsT'ER, on ST. LOUIS, MISSOURI.

PROCESS oF MAKING PIGMENTS.

SPECIFICATION formingpart of Letters Patent No. 740,072, dated September29, 1903. Application filed July 21, 1902. Serial No. 116,456. (Nospecimens.)

To all whom it may concern:

Be it known that 1, WILLIAM J. ARMBRUS- TER, a citizen of the UnitedStates, residing at St. Louis, State of Missouri, have invented certainnew and useful Improvements in Processes of Making Pigments, of whichthe following isa specification.

plates the successive precipitation of barium sulfate and zincsulfid'(or vice versa) from solutions capable of precipitating one orthe other of said compounds, leaving a second or intermediate solutionfrom which can be precipitated'the remaining compound and a resultingsolution corresponding to the first solution,from which can again beprecipitated the first compound, and so on. In otherwords, the solutionremaining as a result of the chemical reactions incident to theprecipitation of one of the compounds serves as a reagent forprecipitating the second compound, and the final solution after suchsecond precipitation corresponds to'the first solution-from which thefirst precipitate was derived. It therefore results in a cyclicalprocess or a process which is self-contained, since it does not resultin any waste product or solution not capable of being utilized as adirect reagent in the process.

The object, therefore, of my process is to avoid the production of anywaste products or any product not capable of being directly employed asa reagent inthe formation of the precipitates constituting thecomposition above referred to.

As an illustration of the general principle above enunciated, I prepareone molecular equivalent of an aqueous solution of sodiumv sulfate towhich I add one equivalent of barium sulfid. The result of the mixtureis a precipitate of one molecular equivalent of barium sulfate and asolution of one equivalent of sodium sulfid. To this intermediatesolution is added one equivalent of a solution of zinc sulfate, whenthere is precipitated on top of the barium sulfate one equivalent of.zinc sulfid, leaving a final or resulting solution of one equivalentofsodium sulfate to be used 'over again with a new addition of bariumsulfid, and so on, so that the process is a continuous one, the solutionremaining after any single precipitation always" serving as a reagentfor the next precipitation. This condition may be expressed by thefollowing reaction: 7

' Ne,so,+nes=1;aso,+Na,s.- Na S+ZnSO =ZnS+Na SO It isof courseimmaterial which solution is the initial one. If we start withthesodiumsulfid solution, the reactions may be expressed as follows;

Na S+ZnSO :ZnS +Na SO Na SO,+BaS=BaSO,-l-Na S. In either casethereresults: the consecutive precipitation of zinc sulfid and bariumsulfate, (or barium sulfate followed by zinc sulfid,) with the furtherresult that the solution remaining after any precipitation is used forasubsequent precipitation, the solutions never passing out of thecyclc ofreagents employed in the process. I may of course substitute any of thealkali metals for the sodium base, as above specified, and as anillustration of such substitution the following reactions, in

which ammonium sulfate and ammonium sulfid are substituted, may becited:

Again, where the sullid of ammonium is the initial solution thefollowing reactions take place:

Since in the present case, as in others, the doctrine of chemicalequivalents can be invoked, it follows that I may substitute(without'departing from the nature of the invention) for the sulfate andsulfid salts of sodium and ammonium the corresponding salts ofpotassium, aluminium, or potassium aluminium, or ammonium aluminium, ora mixture of the aforesaid sulfates or sulfids, respectively. Suchsubstitution will in no wise affect the status or functions of thesolutions resulting from any single precipitation.

The determination of the actual quantities of the materials used in theforegoing reactions is asimplestoicheiometric problem based upon theatomic weights of the elements constituting any molecule, and as acommercial illustration of the formula contained in the first of theabove reactions the following may be cited: I prepare an aqueoussolution of one hundred and forty-two (142) pounds of sodium sulfate andone hundred and sixtynine (169) pounds of barium sulfid and bring themtogether, when there results a precipitate of two hundred andthirty-three (233) pounds of barium sulfate and a solution ofseventy-eight (78) pounds of sodium sulfid. To this is then added asolution containing one hundred and sixty-one (161) pounds'of zincsulfate, when there is precipitated ninetyseven (97) pounds of zincsulfid, leaving a solution containing one hundred and fortytwo (142)pounds of sodium sulfate, the same as at the beginning of the cycle. Theprocess can thus be continued indefinitely.

As the repeated additions of solutions will necessarily increase thebulk of the water or solution after each reaction, means for evaporatingthe excess of Water or solution to a smaller volume at suitable periodscan be provided. Any manner of evaporation known to the art is of courseavailable for this purpose. 7

It is of course apparent that I may invoke the doctrineofchemicalequivalents wherever the same may apply. The precipitates maybe intimately mixed after their recovery from the solutions by any ofthe mechanical methods known in the arts.

Having described my invention, what I claim is- 1. In the manufacture ofpigments the process of adding a solution of barium sulfid to thesulfate of an alkali metal, then adding a soluble zinc salt to theresulting solution, and recovering the final precipitates, substantiallyas set forth.

2. In the manufacture of pigments,the process of adding a solution ofbarium sulfid to a solution of the sulfate of an alkali metal, thenadding a solution of zinc sulfate, and recovering'the resultingprecipitates, substantially as set forth.

. 3. In themanufacture of pigments,the process of adding to a solutionof one molecular equivalent of a sulfate of an alkali metal onemolecular equivalent of a solution of barium sulfid, then adding to theresulting solution a solution of one-molecular equivalent of zincsulfate, and recovering the resulting precipitates, substantially as setforth.

4. In the manufacture of pigments,the process of mixing molecularequivalentsof solutions of the sulfate of sodium and the sulfid ofbarium, then adding a corresponding molecular equivalent ofa solution ofzinc sulfate,

and recovering the resulting precipitates,substantially as set forth.

5. The process of making pigments which consists of mixing a solution ofone molecular equivalent of sodium sulfate, with onemolecular equivalentof barium sulfid, then adding a solution of one molecular equivalent ofzinc sulfate, recovering the precipitates, and continuing the operationindefinitely with a repetition of the addition of the severalsolutionsin the order specified, substantially as set forth.

6. In the manufacture of pigments,the process of adding to a solution ofa sulfate, a solution of barium sulfid, then adding a solu-' tion ofzinc sulfate, and recovering the resulting precipitates, substantiallyas set forth.

In testimony whereof I aflix my signature in presence of two witnesses.

I WILLIAM J. ARMBRUSTER.

\Vitnesses:

EMIL STAREK, G. L. BELFRY.

